1. Field of the Invention
Aspects of one or more embodiments relate to an image forming apparatus and an image forming method and, more particularly, to an image forming apparatus that retains properties of a color image and generates a gray image with high readability and an image forming method thereof.
2. Related Art
Image forming apparatuses now commonly print in color; similarly, virtually all displays now display images and documents in color. If the images and/or documents are printed by a black-and-white image forming apparatus, various colors of the documents (and/or images) are first converted into various shades of gray.
FIG. 1 is a flowchart of a conventional image forming method to convert an RGB image into a gray image. The conventional image forming method includes receiving an RGB image to be printed at block S102, extracting brightness values of respective colors in the RGB image at block S104 and converting the RGB image into the gray image based on the extracted brightness values of the respective colors at block S106 by Formula (0):Gray image=0.2989×R+0.5890×G+0.1140×B 
Here, R is a variable corresponding to the value of a red color channel of the RGB image, G is a variable corresponding to the value of a green color channel of the RGB color image, and B is a variable corresponding to the value of a blue color channel of the RGB color image. If the color image is converted into the gray image by multiplying the brightness values alone, a hue and a saturation of the respective colors of the color image are not distinguished, and colors having similar hue and saturation will have the same brightness. The color image converted into the gray image will not retain the properties of the color image, thereby lowering readability of the gray image.